I get a lot of backfire on decel. TONS more power no more throttle lag too!
Severe backfire through carb but, it seems to go away after a good ride. WOT seems good no change on roll off.
I sprayed WD-40 all over the manifold and couldn't find any leaks (no change in idle after warm)

Steven

check you spigot to intake and exhaust sounds like a leak till she is warmed up. What is the float level and what is your miles to reserve.

I soldered the spigot on intake manifold shut AND put a rubber plug on it.
Float level is set to Mikuni tuning manual. Dunno on reserve yet I've only ridden about 20 miles or so since I installed it. My wife wouldn't let me go for a long ride on Thanksgiving (leaving her alone with 20 guests)

I hope to take it out some more today.

BTW I was riding it at night when it was cooler (54degrees) dunno it that would have an effect too

I have a like new HSR45 with the TPS installed ready to go if you want to mess with it $300 shipped.

Hey Steven , Why ( if you dont mind me asking , and I have followed the thread about your ebay purchase ! ) are you not giving the 45 a try ? Seems to me that if the Jet sizes and nozzels can be matched the only thing different would be the amount of air possible to be sucked in to the intake , which is kind of controlled by the demand capacity . Guess Im trying to talk myself into Buying it from you , Be nice to hear some mikuni HSR experts on the subject like mayby erbman !!!
Sailrider

I was talking about the back of the carb to the manifold are you able to move the carb when mated in out side to side. On exhaust anywhere it has a joint or mating surface. Just trying to not jump the gun to anything. I'm sure you know the pms is air on the 42 not fuel. Is that the needle it came with .
Another way to check the intake is a flash light or a bore light turn the lights out and see if you see any light.

sailrider wrote:I have a like new HSR45 with the TPS installed ready to go if you want to mess with it $300 shipped.

Hey Steven , Why ( if you dont mind me asking , and I have followed the thread about your ebay purchase ! ) are you not giving the 45 a try ? Seems to me that if the Jet sizes and nozzels can be matched the only thing different would be the amount of air possible to be sucked in to the intake , which is kind of controlled by the demand capacity . Guess Im trying to talk myself into Buying it from you , Be nice to hear some mikuni HSR experts on the subject like mayby erbman !!!
Sailrider

My reason for not using the HSR45 is I never plan on moding the engine internally (high comp pistons, boring out etc.) That is the primary use for the 45. There are a few that have used the HSR45 on their R* stock engine (Flashback) but, according to the ones who have the 45 on stock engines it is a little more work to dial it in. I did a lot of research and had my mind set on using a HSR42 so thats what I wanted. If I had not been able to find one for the price I would have gone with the 45 and made it work.

Makcap wrote:I was talking about the back of the carb to the manifold are you able to move the carb when mated in out side to side. On exhaust anywhere it has a joint or mating surface. Just trying to not jump the gun to anything. I'm sure you know the pms is air on the 42 not fuel. Is that the needle it came with .
Another way to check the intake is a flash light or a bore light turn the lights out and see if you see any light.

The carb doesn't move at all I've tightened the clamp really good (removed the spacer) I will try the flashlight too. The exhaust hasn't been touched since I put it on over 20,000 miles ago and I used new gaskets.

I get a lot of backfire on decel. TONS more power no more throttle lag too!
Severe backfire through carb but, it seems to go away after a good ride. WOT seems good no change on roll off.
I sprayed WD-40 all over the manifold and couldn't find any leaks (no change in idle after warm)

Steven

What are your temps where you are? Could be carb coughs from too cold temps too. Don't use wd40 for leaks, get a can of starter fluid. My last leak couldn't find with carb cleaner, but the starter fluid picked it up. did you use the #50 pump nozzle? The 1 1/4 turns seems rich, what resistance did you set the TPS, did you recheck ohms after you tighten the screws? I've seen resistance change after the tps was tightened down, so it needs to be double checked to ensure it didn't change. Winter is the worst time of yr for carb tuning. The severe back fire and excessive carb coughs are lean conditions, sounds like an air leak. manifold vacuum port sealed? at the worst might get a bit more decel popping when cold, but not backfire.

Went for a ride again tonight it was about 50 degrees so not too cold. I rode about 30 miles freeway avg 75mph then down a curvy road to my house, riding hard 3 & 4 gear there was a lot of poping on decel.

I did put the #50 nozzle in.
I didn't do anything to the tps resistance.... I just bolted it on and thats it
I have the PMS to about 3/4 turns out now. It seems a little better. I'm going to take it out again tomorrow for a good ride during the day (70-80's) I will pick up some starter fluid too.

I soldered the manifold vacuum port closed and put a rubber boot on it too.

Except for the popping on decel it runs really good.

Man, I will say it sure adds some power and she sounds like a race car now!

The Road Star Clinic
is a collaborative community of riders who archive and publish user contributed technical
data about Yamaha Road Star motorcycles.

We also sponsor the creation and support of other community websites similar to our own. Inquiries
about availability of a website for your community can be submitted to us via any "Contact Us" option
on the Clinic.

Copyright 2003-2007 Road Star Clinic and its respective authors. Road Star Clinic is sponsored by the folks at MLSHomeQuest.com.